Group iii-nitride light emitting devices including a polarization junction

ABSTRACT

Light emitting devices employing one or more Group III-Nitride polarization junctions. A III-N polarization junction may include two III-N material layers having opposite crystal polarities. The opposing polarities may induce a two-dimensional charge carrier sheet within each of the two III-N material layers. Opposing crystal polarities may be induced through introduction of an intervening material layer between two III-N material layers. Where a light emitting structure includes a quantum well (QW) structure between two Group III-Nitride polarization junctions, a 2D electron gas (2DEG) induced at a first polarization junction and/or a 2D hole gas (2DHG) induced at a second polarization junction on either side of the QW structure may supply carriers to the QW structure. An improvement in quantum efficiency may be achieved where the intervening material layer further functions as a barrier to carrier recombination outside of the QW structure.

BACKGROUND

Solid state light emitting devices, or light emitters, find widespreadapplications from electronic displays to general illumination. Somedisplay technology, referred to as crystalline light emitting diode(LED), or as inorganic LED (iLED), employ an array of crystallinesemiconductor LED chips. Each emitter of an LED chip typically includesa Group III-Nitride (III-N) heterostructure having a plurality of III-Nmaterial layers including a quantum well (QW) structure. The QWstructure is to confine electrons and holes so they may recombine togenerate photons of a desired wavelength (color). Devices for generalillumination applications may also rely on emitters having a III-Nheterostructure that includes an QW structure. A laser is an example ofanother light emitting device that may likewise have a plurality ofIII-N material layers including a QW structure. Additional mirrorstructures (e.g., Bragg reflectors, etc.) may be included within a lightemitter to induce lasing.

Internal quantum efficiency (QE) of a light emitter is the measure ofhow efficiently the emitter converts injected charge carriers (electronsand holes) into photons (light). High current densities are required inapplications where high light output is required from a small areadevice, such as a display, automotive headlights, and micro-LEDapplications. III-N light-emitting diodes and lasers can suffer a lossof IQE at high current densities. This loss in IQE at high currentdensities may be due, at least in part, to poor electron confinementwithin the QW structure and also poor injection efficiency of holes fromp-GaN into the QW structure.

To date, attempts to mitigate this LED efficiency droop have includedintroducing one or more electron blocking layers (EBLs) within a III-Nheterostructure. An EBL is generally a III-N material (e.g., AlGaN) thathas a wider band gap than the QW structure (e.g., InGaN/GaN bilayers).The EBL improves the confinement of the electrons in the QW, for exampleby blocking electrons in the conduction band from rushing towards ap-type terminal material (e.g., p-GaN) where it can be lost vianon-radiative recombination with free carrier holes. However, becausethe EBL also introduces a valence band offset, the EBL also creates abarrier that blocks the injection of holes from the p-type terminal intothe QW structure. This hole blocking reduces the injection efficiency ofhole injection. To improve the hole injection efficiency, EBLs may beinterleaved with lower bandgap layers (e.g., InGaN) in a superlatticestructure that ideally permits the quantum mechanical tunneling of holesfrom p-type terminal material to the QW structure. However, the EBLbarrier to electrons in the conduction band is also effectively loweredby this superlattice because electrons can now also tunnel from the QWstructure to the p-type terminal without participating in radiativerecombination. New light emitter architectures that may avoid theselimitations are therefore advantageous.

BRIEF DESCRIPTION OF THE DRAWINGS

The material described herein is illustrated by way of example and notby way of limitation in the accompanying figures. For simplicity andclarity of illustration, elements illustrated in the figures are notnecessarily drawn to scale. For example, the dimensions of some elementsmay be exaggerated relative to other elements for clarity. Also, variousphysical features may be represented in their simplified “ideal” formsand geometries for clarity of discussion, but it is nevertheless to beunderstood that practical implementations may only approximate theillustrated ideals. For example, smooth surfaces and squareintersections may be drawn in disregard of finite roughness,corner-rounding, and imperfect angular intersections characteristic ofstructures formed by nanofabrication techniques. Further, whereconsidered appropriate, reference labels have been repeated among thefigures to indicate corresponding or analogous elements. In the figures:

FIG. 1A is a schematic of a device with a LED circuit, in accordancewith some embodiments;

FIG. 1B is a schematic of a device with a laser circuit, in accordancewith some embodiments;

FIG. 2 is an isometric illustration showing crystal polarity inversionat a III-N polarization junction, in accordance with some embodiments;

FIG. 3 is a cross-sectional view of a light emitter structure includingthe III-N polarization junction shown in FIG. 2, in accordance with someembodiments:

FIG. 4 is an isometric illustration showing crystal polarity inversionat a III-N polarization junction, in accordance with some embodiments;

FIG. 5 is a cross-sectional view of a light emitter structure includingthe III-N polarization junction shown in FIG. 4, in accordance with someembodiments;

FIG. 6A is a cross-sectional view of a light emitter structure employinga QW structure between a P-type polarization junction and an N-typeimpurity-doped terminal, in accordance with some embodiments;

FIG. 6B is a cross-sectional view of a light emitter structure employinga QW structure between a P-type polarization junction and an N-typeimpurity-doped terminal, in accordance with some alternativeembodiments;

FIG. 7 is a cross-sectional view of a light emitter structure employinga QW structure between two polarization junctions, in accordance withsome alternative embodiments;

FIG. 8 is a flow diagram illustrating methods of forming a lightemitter, in accordance with some embodiments:

FIGS. 9A, 9B, 9C, 9D, 9E, 9F, 9G, and 9H are cross-sectional views of alight emitter evolving as selected operations in the methods illustratedin FIG. 8 are performed, in accordance with some embodiments;

FIG. 10 illustrates a mobile computing platform and a data servermachine employing an IC including a light emitter, in accordance withembodiments; and

FIG. 11 is a functional block diagram of an electronic computing device,in accordance with some embodiments.

DETAILED DESCRIPTION

One or more embodiments are described with reference to the enclosedfigures. While specific configurations and arrangements are depicted anddiscussed in detail, it should be understood that this is done forillustrative purposes only. Persons skilled in the relevant art willrecognize that other configurations and arrangements are possiblewithout departing from the spirit and scope of the description. It willbe apparent to those skilled in the relevant art that techniques and/orarrangements described herein may be employed in a variety of othersystems and applications other than what is described in detail herein.

Reference is made in the following detailed description to theaccompanying drawings, which form a part hereof and illustrate exemplaryembodiments. Further, it is to be understood that other embodiments maybe utilized and structural and/or logical changes may be made withoutdeparting from the scope of claimed subject matter. It should also benoted that directions and references, for example, up, down, top,bottom, and so on, may be used merely to facilitate the description offeatures in the drawings. Therefore, the following detailed descriptionis not to be taken in a limiting sense and the scope of claimed subjectmatter is defined solely by the appended claims and their equivalents.

In the following description, numerous details are set forth. However,it will be apparent to one skilled in the art, that the presentinvention may be practiced without these specific details. In someinstances, well-known methods and devices are shown in block diagramform, rather than in detail, to avoid obscuring the present invention.Reference throughout this specification to “an embodiment” or “oneembodiment” or “some embodiments” means that a particular feature,structure, function, or characteristic described in connection with theembodiment is included in at least one embodiment of the invention.Thus, the appearances of the phrase “in an embodiment” or “in oneembodiment” or “some embodiments” in various places throughout thisspecification are not necessarily referring to the same embodiment ofthe invention. Furthermore, the particular features, structures,functions, or characteristics may be combined in any suitable manner inone or more embodiments. For example, a first embodiment may be combinedwith a second embodiment anywhere the particular features, structures,functions, or characteristics associated with the two embodiments arenot mutually exclusive.

As used in the description and the appended claims, the singular forms“a”, “an” and “the” are intended to include the plural forms as well,unless the context clearly indicates otherwise. It will also beunderstood that the term “and/of” as used herein refers to andencompasses any and all possible combinations of one or more of theassociated listed items.

The terms “coupled” and “connected,” along with their derivatives, maybe used herein to describe functional or structural relationshipsbetween components. It should be understood that these terms are notintended as synonyms for each other. Rather, in particular embodiments,“connected” may be used to indicate that two or more elements are indirect physical, optical, or electrical contact with each other.“Coupled” may be used to indicated that two or more elements are ineither direct or indirect (with other intervening elements between them)physical or electrical contact with each other, and/or that the two ormore elements co-operate or interact with each other (e.g., as in acause an effect relationship).

The terms “over,” “above,” “under,” “below,” “between,” and “on” as usedherein refer to a relative position of one component or material withrespect to other components or materials where such physicalrelationships are noteworthy. For example in the context of materials,one material or material over/above or under/below another may bedirectly in contact or may have one or more intervening materials.Moreover, one material between two materials may be directly in contactwith the two layers or may have one or more intervening material layers.In contrast, a first material “on” a second material is in directcontact with that second material/material. Similar distinctions are tobe made in the context of component assemblies.

As used throughout this description, and in the claims, a list of itemsjoined by the term “at least one of” or “one or more of” can mean anycombination of the listed terms. For example, the phrase “at least oneof A. B or C” can mean A; B; C; A and B; A and C; B and C; or A. B andC.

Light emitters employing one or more III-N polarization junctions aredescribed herein. As described further below, a III-N heterostructurethat includes a plurality of III-N material layers, or lamella, ofdifferent crystal polarities may be employed within a light emitter.Light emitter structures in accordance with some embodiments include apolarity inversion between a first layer of III-N material and a secondlayer of III-N material. The first and second III-N material layers maybe separated by an intervening material layer that facilitates thepolarity inversion. The polarity inversion may induce a firsttwo-dimensional charge carrier sheet of a first type (e.g., a twodimensional hole gas or “2DHG”) within each of the first and secondlayers of III-N material, for example near their interface with theintervening material layer. Light emitter structures further include aquantum well (QW) structure above, below, or otherwise adjacent to, thepolarization junction. The charge carrier sheet may supply first chargecarriers (e.g., holes) for recombination within the QW structure. Theintervening material layer at the polarization junction may furtherconfine charge carriers (e.g., electrons), concurrently achievingimprovements in carrier injection efficiency and carrier confinementwithin the light emitter structure. As such, higher IQE may be achievedfor light emitter structures having one or more of the architecturesdescribed further below. Light emitter architectures in accordance withone or more of the embodiments described herein may eliminate the needto introduce other electron confinement structures (e.g., EBLs) thatdetrimentally impact hole injection. Alternatively, light emitterarchitectures in accordance with one or more of the embodimentsdescribed herein may be combined with other electron confinementstructures to enhance their effect.

Light emitter structures in accordance with some embodiments furtherinclude a second polarity inversion between the first layer of III-Nmaterial and a third layer of III-N material. The first and third layersof III-N material may be separated by a second intervening materiallayer that facilitates the second polarity inversion. The secondpolarity inversion may induce a second two-dimensional charge carriersheet of a complementary type (e.g., a two dimensional hole gas or“2DEG”) within each of the first and third III-N material layers, forexample near their interface with the second intervening material layer.The charge carrier sheets induced at each crystal inversion may be onopposite sides of a QW structure. The charge carrier sheets aredependent upon the spontaneous and piezoelectric polarization of theIII-N material layers and are additive, resulting in very high carrierdensities. Hence, with multiple polarization junctions, light emitterperformance may exceed that of other emitter architectures. Lightemitter architectures in accordance with some embodiments may alsoenable lower contact resistance with terminal semiconductor material,particularly where a doping junction couples to a region of chargecarrier sheet that scales with the area of semiconductor materialinterface.

Embodiments described herein are applicable to many semiconductor lightemitter architectures, such as, but not limited to, light emittingdiodes (LEDs) and lasers. The term “light emitter” is employed herein torefer to a broad class of semiconductor device architectures known toemit light. FIG. 1A is a schematic of a platform 101 that includes alight emission circuit with at least one LED 105 coupled to an emitterdriver circuit 115, in accordance with some embodiments. The lightemission circuit may be implemented by one or more IC chip, discretecomponents and combinations thereof. Platform 101 may be an electronicdevice, such as, but not limited to, a display, smartphone, ultrabookcomputer, embedded devices (e.g., internet of things, automotiveapplications, general illumination applications, etc.), wearables, andthe like. During operation, driver 115 is to deliver a controlledvoltage and/or current to LED 105. LED 105 may include a first terminalcoupled to a first supply rail of driver 115 maintained at a nominalsupply voltage (e.g., V_(cc)). LED 105 may further include a secondterminal coupled to second supply rail maintained at a nominal referencevoltage (e.g., Vs). Under forward bias, LED diode 105 is to emit lightwithin a band of the electromagnetic spectrum including one or more ofthe near infrared (NIR), the visible spectrum (including bluewavelengths of 380-405 nm), and ultraviolet wavelengths. As describedfurther below, LED 105 includes a QW structure and at least one III-Npolarization junction. The improved performance (e.g., higher IQE) ofLED 105 may advantageously reduce the energy consumption of platform101, and/or improve the optical output power of platform 101.

FIG. 1B is a schematic of a platform 102 that includes a light emissioncircuit with at least one laser diode 110 coupled to emitter drivercircuit 115, in accordance with some embodiments. The light emissioncircuit may be implemented by one or more IC chip, discrete componentsand combinations thereof. Platform 102 may be an electronic device, suchas, but not limited to, a display, smartphone, ultrabook computer,embedded devices (e.g., internet of things, automotive applications,general illumination applications, etc.), wearables, and the like.During operation, driver 115 is to deliver a controlled voltage and/orcurrent to laser 110. Laser 110 may include a first terminal coupled toa first supply rail of driver 115 maintained at a nominal supply voltage(e.g., V_(cc)). Laser 110 may include a second terminal coupled tosecond supply rail maintained at a nominal reference voltage (e.g.,V_(ss)). Under forward bias, stimulated emission occurs within a band ofthe electromagnetic spectrum including one or more of the near infrared(NIR), the visible spectrum (including blue wavelengths of 380-405 nm),and ultraviolet wavelengths. Laser 110 may include a QW structure and atleast one III-N polarization junction, substantially as described below.The improved performance (e.g., higher IQE) of such a laser mayadvantageously reduce the energy consumption of platform 102, and/orimprove the optical output power of platform 102.

FIG. 2 is an isometric illustration showing crystal polarity inversionof a III-N polarization junction 201, in accordance with someembodiments. FIG. 3 is a cross-sectional view of a light emitterstructure 301 structure that integrates the III-N polarization junction201 with a QW structure that further includes one or more QW layer 655,in accordance with some embodiments. Either of LED 105 (FIG. 1A) orlaser 110 (FIG. 1B) may have one or more of the features furtherdescribed below in the context of III-N polarization junction 201, orlight emitter structure 301, for example.

As shown in FIG. 2, polarization junction 201 includes a first GroupIII-nitride (III-N) material layer 220, an intervening material layer250, and a second III-N material layer 230. Although illustrated aslayers for the sake of simplification, it is noted that equivalentreferences may be made to laterally (horizontally) arranged III-Nmaterials. III-N material layer 220 may be any III-N material, such as abinary alloy (e.g., GaN, AlN, InN), a temary alloy (e.g.,Al_(x)In_(1-x)N, In_(x)Ga_(1-x)N, or Al_(x)Ga_(1-x)N), or quatemaryalloy (e.g., In_(x)Ga_(y)Al_(1-x-y)N). III-N material layer 230 maylikewise be any III-N material. In some embodiments, III-N materiallayer 230 has the same composition as III-N material layer 220. In otherembodiments, III-N material layer 230 has a composition distinct fromIII-N material layer 220. III-N material layer 230 may be, for example,a binary alloy (e.g., GaN. AlN, InN), a ternary alloy (e.g.,Al_(x)In_(1-x)N, In_(x)Ga_(1-x)N, or Al_(x)Ga_(1-x)N), or quaternaryalloy (e.g., In_(x)Ga_(y)Al_(1-x-y)N). In some advantageous embodiments,III-N material layers 220 and 230 are intrinsic and not intentionallydoped with impurities associated with a particular conductivity type.Intrinsic impurity (e.g., Si) levels in III-N material layers 220 and230 may be advantageously less than 1e17 atoms/cm³, and in someexemplary embodiments is between 1e14 and 1e16 atoms/cm³. In some ofthese embodiments, III-N material layers 220 and 230 are both intrinsicbinary GaN (i-GaN).

III-N material layers 220 and 230 may each have monocrystallinemicrostructure (e.g., hexagonal Wurtzite). Although monocrystalline, itis noted that crystal quality of the III-N crystal may varydramatically, for example as a function of the techniques employed toform material layers 220 and 230. In some exemplary embodiments,dislocation density with III-N material layers 220 and 230 is in therange of 10-10¹¹/cm². FIG. 2 illustrates crystal orientations of III-Nmaterial layers, 220 and 230, in accordance with some embodiments. Thecrystal structure of III-N material layer 220 lacks inversion symmetry,as does the crystal structure of III-N material layer 230. As shown,III-N material layer 220 has a polar group III (e.g., Ga)-face and apolar nitrogen (N)-face. Higher order planes may be semi-polar. The(0001) and (000-1) planes are not equivalent. Relative to a plane ofintervening material layer 250, III-N material layer 220 may becharacterized as having +c polarity with the c-axis extending in the<0001> direction that is out of the plane of intervening material layer250, and/or of an underlying substrate (not depicted). The orientationof III-N material layer 220 may therefore be referred as Group III-face,or III-face III-N, or (000-1) III-N, or as having Group III-polarity(+c). The crystal orientation of III-N material layer 230 is invertedrelative to that of III-N material layer 220, and may be characterizedhas having −c polarity with the c-axis extending in the <000-1>direction out of the plane intervening material layer 250, and/or of anunderlying substrate. The orientation of III-N material layer 230 maytherefore be referred as N-face, (e.g., N-face III-N), or as (000-1)III-N, or as having N-polarity (−c).

As further illustrated in FIG. 3, because the crystal orientation, orcrystal polarity, of III-N material layer 230 is inverted with respectto that of III-N material layer 220, the c-axes of III-N material layers220 and 230 are aligned substantially anti-parallel. Althoughillustrated as anti-parallel, it is noted that the crystal orientationsof material layers 220 and 230 may vary by 5-10° from an anti-paralleltarget as a result of processing conditions, and the impact of suchmisalignment of the crystals may merely be a slight reduction inpolarization field strength. The junction between III-N material layers220 and 230 is referred to herein as a “polarization junction” for atleast the reason that crystals of different polarization or polaritymeet (e.g., at their interface with intervening material layer 250).III-N material layer 220 is associated with a polarization fieldstrength P₁ that is a function of spontaneous and/or piezoelectricpolarization field strength for the selected III-N alloy composition.III-N material layer 230 is likewise associated with a polarizationfield strength P₂ that is a function of spontaneous and/or piezoelectricpolarization field strength for the selected III-N alloy composition.Because of the anti-parallel polarities of III-N material layer 220 andIII-N material layer 230, two dimensional charge carrier (gas) sheets375 and 376 are formed within at least a portion of III-N materiallayers 220, 230 proximal to their interface (e.g., proximal tointervening material layer 250). Notably, because of the anti-parallelcrystal polarities, the two dimensional charge carrier sheets 375 and376 are induced by a summation of the polarization field strengths P₁and P₂. This is in contrast to a charge carrier gas that may be inducedas a result of differences between the polarization field strengths oftwo different III-N compositions at a heterojunction having a singlecrystal polarity. Hence, in some exemplary embodiments where III-Nmaterial layers 220 and 230 have the same composition (e.g., both arei-GaN), polarization field strength P1 is equal to polarization fieldstrength P2 (i.e., P1=P2). Following Maxwell's equations, the twodimensional charge carrier sheets 375 and 376 are then are result of afield equal to P2+P2, or 2*P2. Thus, very high charge carrier densitiesmay be present within a few nanometers on either side of polarizationjunction 201.

The relative crystal orientations shown in FIGS. 2 and 3 induce positivecharge carrier sheets 375, 376. Because the anti-parallel polarizationfields of III-N material layers 220, 230 point away from polarizationjunction 201, the resultant polarization doping is P-type. Polarizationjunction 201 (FIG. 2) may therefore be referred to as a P-typepolarization junction. Positive charge carrier sheets 375, 376 may alsobe referred to as two-dimensional hole gases (2DHG). These 2DHGs are theresult of III-N material layer 220 having the polar Group III-face(e.g., Ga-face) adjacent to intervening material layer 250 and the polarN-face opposite, or distal to, intervening material layer 250. III-Nmaterial layer 230 also has the Group III-face (e.g., a Ga-face)adjacent to intervening material layer 250, and the nitrogen (N)-faceopposite, or distal to, intervening material layer 250. Positive chargecarrier sheets 375, 376 may be proximal (e.g., with 2-4 nm) to theinterface of intervening material layer 250. In some such embodimentsIII-N material layer 230 therefore has a thickness of at least 3 nm, andmay be less than 10 nm.

Intervening material layer 250 may be any material or materials suitablefor facilitating the formation of polarization junction 201. Forexample, in some embodiments intervening material layer 250 includes amaterial that facilitates a crystal polarity inversion during anepitaxial growth of III-N material layer 230. For such embodiments,intervening material layer 250 may be (mono)crystalline. As anotherexample, in some embodiments intervening material layer 250 includes amaterial that facilitates a bonding of III-N material layer 230 to III-Nmaterial layer 220. For such embodiments, intervening material layer 250may be monocrystalline, polycrystalline, or amorphous. In some amorphousor (poly)crystalline embodiments, intervening material layer 250 is adiscontinuous film layer that comprises islands of amorphous or(poly)crystalline material dispersed over the surface of III-N materiallayer 230. Intervening material layer 250 may have any suitablethickness (e.g., along the c-axis). In some embodiments, interveningmaterial layer 250 has a thickness not more than 5 nm, andadvantageously not more than 3 nm. In an embodiment, interveningmaterial layer 250 is a crystalline material including less than 10,advantageously less than 7, and potentially even less than 5 monolayers.

In some exemplary crystalline embodiments, intervening material layer250 has other than hexagonal crystallinity (i.e., crystallinity otherthan that of III-N material layers 220, 230). In some examples,intervening material layer 250 may have trigonal crystallinity. In someother examples, intervening material layer 250 may have cubiccrystallinity. Having crystallinity other than that of the III-Nmaterial system may advantageously facilitate polarity inversion whilestill providing a crystalline seeding surface that can maintainmonocrystallinity of III-N material layer 230, for example. In someexemplary embodiments, intervening material layer 250 is other than aIII-N material (e.g., other than a binary, temary or quatemary III-Nalloy). Intervening material layer 250 may, for example, include one ormore of oxygen, a metal, or a metalloid. The metal may more specificallybe a rare earth, a lanthanide, a transition metal, or a post-transition(e.g., group III) metal. In some exemplary embodiments, interveningmaterial layer 250 is, or includes, aluminum oxide (Al_(x)O_(y)). Insome such embodiments, intervening material layer 250 is crystallinealuminum oxide (e.g., sapphire). In some other embodiments, interveningmaterial layer 250 is, or includes, scandium oxide (Sc_(x)O_(y)). Insome other embodiments, intervening material layer 250 is, or includes,scandium nitride (Sc_(x)N_(y)) material, aluminum oxy-nitride (AlNO), orscandium oxy-nitride (ScNO). In some such embodiments, interveningmaterial layer 250 is crystalline scandium oxide. In still otherembodiments, intervening material layer 250 is, or includes, a mixedmetal alloy, such as, but not limited to, aluminum scandium oxide.

Although in some embodiments, intervening material layer 250 is indirect contact with both III-N material layer 220 and III-N materiallayer 230, one or more material layers may also separate interveningmaterial layer 250 from III-N material layer 220 and/or from interveningmaterial layer 230. For example, intervening material layer 250 may bewithin a stack of material layers separating III-N material layer 220from III-N material layer 230. In some embodiments, intervening materiallayer 250 is in contact with (e.g., on or under) a (mono)crystallinealuminum nitride (AlN) layer, or other crystalline III-N materialsuitable as an epitaxial nucleation layer. For example, interveningmaterial layer 250 may be an oxide of an underlying AlN layer, or anoxide of an overlying AlN layer. In either case, intervening materiallayer 250 may be predominantly Al_(x)O_(y) Intervening material layer250 may also be between two (mono)crystalline AlN layers. For example,intervening material layer 250 may be a layer of aluminum oxide locatedbetween a first and a second (mono)crystalline aluminum nitride layer.

In some amorphous or (poly)crystalline embodiments, intervening materiallayer 250 is, or includes, one or more of, aluminum oxide, siliconoxide, silicon nitride, silicon oxynitride, hafnium oxide, hafniumsilicon oxide, lanthanum oxide, lanthanum aluminum oxide, zirconiumoxide, zirconium silicon oxide, tantalum oxide, titanium oxide, bariumstrontium titanium oxide, barium titanium oxide, strontium titaniumoxide, yttrium oxide, tantalum oxide, tantalum silicon oxide, leadscandium tantalum oxide, and lead zinc niobate. These oxides can have arelatively high degree of crystallinity, for example when deposited withatomic layer deposition.

As further illustrated in FIG. 3, light emitter structure 301 furtherincludes a QW structure that is electrically coupled to a first side ofpolarization junction 201. In the illustrated embodiment, III-N materiallayer 220 may be considered part of the QW structure with at least oneQW layer 655 interleaved within III-N material layer 220. The QWstructure has one crystal polarity with both QW layer 655 and III-Nmaterial layer 220 having the same polarity (e.g., +c). QW structures inaccordance with embodiments herein may have any number of QW layers(e.g., 1, 2, 3, or more). QW layer 655 may be of any III-N materialcomposition that has a smaller bandgap than that of III-N material layer220. QW layer 655 may be, for example, a binary alloy (e.g., GaN, InN),a temary alloy (e.g., Al_(x)In_(1-x)N, In_(x)Ga_(1-x)N, orAl_(x)Ga_(1-x)N), or quatemary alloy (e.g., In_(x)Ga_(y)Al_(1-x-y)N).The bandgap and thickness of QW layer 655 may be selected to emit lightat a predetermined wavelength. For some exemplary embodiments, QW layer655 comprises In_(x)Ga_(1-x)N with x varying between 0.02 and 0.41. Oneor more such QW layer may be interleaved within GaN, for example. QWlayer 655 may have any thickness known to be suitable for such anemission layer, and may for example be limited to thicknesses capable ofquantum carrier confinement. In some embodiments, QW layer 655 has athickness of a few nanometers to a few tens of nanometers. QW layer 655may be intrinsic (not intentionally doped) or may be doped with eitherp-type (acceptor) impurities or n-type (donor) impurities. Likewise,portions of III-N material layer 220 between QW layers 655 may also beintrinsic, or may be doped to the same conductivity type as an adjacentQW layer 655.

With polarization junction 201 inducing the positive charge carriersheet 375, any terminal layer 305 may serve as a source of negativecharge carriers, which during the operation of light emitter structure301 are to radiatively combine with holes supplied by positive chargecarrier sheet 375 as illustrated in FIG. 3 by solid line arrows.Terminal layer 305 may vary with implementation with a few exemplaryembodiments described further below. Embodiments of light emitterstructure 301 are not limited in this context however, and thereforeterminal layer 305 is illustrated in dashed line. As further illustratedby a dashed line arrow in FIG. 3, any negative charge carriers thatmanage to transit all QW layers 655 without combining radiatively, willencounter intervening material layer 250. In exemplary embodiments,intervening material layer 250 poses a significant energy barrier tosuch negative charge carriers, for example largely preventing negativecharge carrier transit through intervening material layer 250.Intervening material layer 250 therefore confines negative chargecarriers to within III-N material layer 220 (and the QW layers therein).Loss of IQE, for example associated with greater electron mobility inIII-N materials and/or lower hole injection efficiency, may bediminished through this electron blocking or confinement by interveningmaterial layer 250. A contact terminal 310 may be made to charge carriersheet 376 and/or or charge carrier sheet 375. Contact terminal 310 mayadvantageously bypass intervening material layer 250 so that holeinjection is not also blocked by intervening material layer 250. Someexemplary structures are further described below. However, embodimentsof light emitter structure 301 are not limited in this context, andtherefore terminal 310 is illustrated in dashed line. Regardless of howpositive carriers are supplied to charge carrier sheet 375, the areaover which hole injection may occur may be advantageously large becausecharge carrier sheet 375 is present over the entire area of QW layer655. Also, the high density of states associated with charge carriersheet 375 may provide an advantageously high hole injection rate perunit area of QW layer(s) 655. These factors, alone or in combination,may enable light emitter structure 301 to achieve high IQE duringoperation.

QW layers 655 are illustrated in FIG. 3 as being separated fromintervening material layer 250 by a thickness of III-N material layer220. In some embodiments where charge carrier sheet 375 is within 2-4 nmof intervening material layer 250, III-N material layer 220 betweenintervening material layer 250 and the QW layer 655 nearest tointervening material layer 250 has a thickness of at least 3 nm, and mayalso be less than 10 nm. In alternative embodiments, the interveningmaterial layer may instead interface with a QW layer. For example, inFIG. 3, intervening material layer 250 may be in direct contact with QWlayer 655, with QW layer 655 then located between intervening materiallayer 250 and III-N material layer 220. Charge carrier sheet 375 maythen reside within QW layer 655. Hole injection may be directly into QWlayer 655.

FIG. 4 is an isometric illustration showing crystal polarity inversionat a III-N polarization junction 401, in accordance with someembodiments. FIG. 5 is a cross-sectional view of a light emitterstructure 501 that includes III-N polarization junction 401 and a QWstructure including one or more QW layer 655, in accordance with someembodiments. Either of LED 105 (FIG. 1A) or laser 110 (FIG. 1B) may haveone or more of the features further described below in the context ofIII-N polarization junction 201, or light emitter structure 301, forexample.

As shown in FIGS. 4 and 5, polarization junction 401 includes the III-Nmaterial layers 220, and 230 with intervening material layer 250 againlocated between these layers. The reference numbers introduced in thecontext of FIG. 2 and FIG. 3 are retained in FIG. 4 and FIG. 5 formaterial layers that may have any of the properties described above inthe context of polarization junction 201 and light emitter structure301. Polarization junction 401 is however a N-type polarization junctionwith two dimensional (2D) charge carrier sheets 575 and 576 beinghigh-density two-dimensional electron gases (2DEG). Negative chargecarrier sheets 575 and 576 may be proximal (e.g., with 2-4 nm) of theinterface of intervening material layer 250. The 2DEGs are the result ofIII-N material layers 220 and 230 having swapped positions relative tothose introduced in the context of FIGS. 2 and 3.

In FIG. 4 and FIG. 5, III-N material layer 220 has the N-face adjacentto intervening material layer 250 and the Group III face (e.g., Ga-face)opposite, or distal to, intervening material layer 250. III-N materiallayer 230 also has the N-face adjacent to intervening material layer250, and the Group III-face (e.g., a Ga-face) opposite, or distal to,intervening material layer 250. III-N material layer 220 is againassociated with polarization field strength P₁ that is a function ofspontaneous and/or piezoelectric polarization field strength for theselected III-N alloy composition. III-N material layer 230 is likewiseassociated with polarization field strength P₂. Because of thesubstantially anti-parallel polarities of III-N material layer 220 andIII-N material layer 230, two dimensional charge carrier sheets 575 and576 are formed within at least a portion of III-N material layers 220,230 proximal to their interface (e.g., proximal to intervening materiallayer 250). Notably, the two dimensional charge carrier sheets 575 and576 are induced by a summation of the polarization field strengths P1and P2. In some exemplary embodiments where III-N material layers 220and 230 interfacing intervening material layer 250 have the samecomposition (e.g., both are i-GaN), polarization field strength P1 isequal to polarization field strength P2 (i.e., P1=P2). FollowingMaxwell's equations, the two dimensional charge carrier sheets 575 and576 are then the result of a field equal to −P2-P2, or −2*P2. Thus,because the anti-parallel polarization fields of III-N material layers220, 230 point toward polarization junction 401, the resultantpolarization doping is complementary to that associated withpolarization junction 201 (FIG. 2).

Intervening material layer 250 may be any of the materials describedabove. As further illustrated in FIG. 5, light emitter structure 501further includes a QW structure that is electrically coupled to a firstside of polarization junction 401. In the illustrated embodiment, III-Nmaterial layer 230 may be considered part of the QW structure with atleast one QW layer 655 interleaved within III-N material layer 230. TheQW structure has one crystal polarity with both QW layer 655 and III-Nmaterial layer 230 having the same polarity (e.g., +c). QW layer(s) 655and III-N material layer 230 may be of any III-N material composition,such as any of those materials described above for QW layer(s) 655 andIII-N material layer 230 in the context of FIGS. 2 and 3.

Polarization junction 401 may be above any terminal layer 305.Embodiments of light emitter structure 501 are not limited in thiscontext, and terminal layer 305 is therefore again illustrated in dashedline. Terminal layer 305 may serve as a source of negative chargecarriers that are to be injected into QW layer(s) 655, which are toradiatively combine with holes supplied by terminal 310, as illustratedin FIG. 5 by solid line arrows. Terminal 310 may vary withimplementation and is also illustrated in dashed line. In one exemplaryembodiment, terminal 310 includes polarization junction 201, as furtherdescribed below. In an alternative embodiment, terminal 310 includes animpurity-doped semiconductor junction.

Positive charge carriers that manage to transit all QW layers 655without combining radiatively will encounter intervening material layer250. In exemplary embodiments, intervening material layer 250 poses asignificant energy barrier to such positive charge carriers, for examplelargely preventing positive charge carrier transit through interveningmaterial layer 250. Intervening material layer 250 may also confinenegative charge carriers substantially as described above. As describedfurther below, a contact terminal may be made to charge carrier sheet576, bypassing intervening material layer 250 so that electron injectionis not also blocked by intervening material layer 250. Some exemplarystructures are further described below, however embodiments of lightemitter structure 501 are not limited in this context. Regardless of hownegative carriers are supplied to charge carrier sheet 576, becausecharge carrier sheet 576 is present over the entire area of QW layer655, the area over which electron injection may occur may beadvantageously large. Also, the high density of states associated withcharge carrier sheet 576 may provide an advantageously high electroninjection rate per unit area of QW 655.

Although QW layers 655 are illustrated in FIG. 5 as being separated fromintervening material layer 250 by a thickness of III-N material layer220, in alternative embodiments, the intervening material layer mayinstead interface with a QW layer. For example, in FIG. 5, interveningmaterial layer 250 may be in direct contact with QW layer 655, with QWlayer 655 then located between intervening material layer 250 and III-Nmaterial layer 220. Charge carrier sheet 575 may then reside within QWlayer 655. Electron injection may then be directly into QW layer 655where they may accumulate at QW layer 655 because of blocking byintervening material layer 250.

FIG. 6A is a cross-sectional view of a light emitter structure 601employing a QW structure between a P-type polarization junction and anN-type impurity-doped terminal, in accordance with some embodiments.Light emitter structure 601 has a vertical architecture with two lightemitter terminals on opposite sides of the QW structure. One of theterminals makes contact to a charge carrier sheet induced by thepolarization junction, while the other terminal is coupled to the QWstructure through an impurity-doped semiconductor. During operation of alight emitter incorporating light emitter structure 601, current willpass through a thickness (e.g., z-dimension) of the QW structure on abottom side of polarization junction 201.

As shown, light emitter structure 601 includes a terminal 610 thatincludes terminal material 380 and a contact metallization 390. Terminalmaterial 380 is operable as a low resistance semiconductor coupling to afirst side of the QW structure that includes III-N material layer 220and QW layer(s) 655. Contact metal 390 may include any metallizationknown to be suitable for providing a non-rectifying contact (e.g., ohmicor tunneling metal-semiconductor junction) to terminal material 380. Insome exemplary embodiments, contact metal 390 includes at least onemetal, such as Ti, Al, or W. In the illustrative embodiment, terminalmaterial 380 is a III-N material having the same crystal orientation(e.g., +c polarity) as III-N material layer 220, and may advantageouslyinclude one or more impurity dopants imparting a desired conductivitytype (e.g., N-type). In some exemplary embodiments, terminal material380 includes a donor impurity dopant such as Si or Ge. In some suchembodiments, the donor impurity concentration is at least 1e18/cm³within terminal material 380, and advantageously 1e19/cm³, or more.Terminal material 380 may form a homojunction with III-N material layer220, or terminal material 380 may form a heterojunction with III-Nmaterial layer 220. Hence, terminal material 380 may have the samemajority lattice constituents as III-N material layer 220 or includeother majority lattice constituents. In some advantageous embodiments,lower contact resistance may be achieved where terminal material 380forms a heterojunction (e.g., abrupt or graded) with III-N materiallayer 220. In some exemplary embodiments, terminal material 380 has anarrower band gap than that of III-N material layer 220. For example,terminal material 380 may be a III-N alloy that includes more Indium(In) than III-N material layer 220. In some embodiments, terminalmaterial 380 is donor-doped In_(x)Ga_(1-x)N, (e.g., where x is between0.05 and 0.2). Terminal material 380 may have any thickness permissibleas a function of its conductivity.

As further illustrated in FIG. 6A, polarization junction 201 isseparated from terminal material 380 by a QW structure that includes atleast one QW layer 655 within III-N material layer 220. QW layer(s) 655and III-N material layer 220 may have any of the properties describedabove in the context of FIGS. 2 and 3, for example. As illustrated, QWlayers(s) 655 and III-N material layer 220 form bi-layers or asuperlattice having the same (+c) polarity as terminal material 380. Aportion of III-N material layer 220 between terminal material 380 and afirst QW layer 655 may have any thickness, but is advantageously lessthan 10 nm. In some further embodiments, III-N material layer 220between terminal material 380 and a first QW layer 655 has a thicknessless than 10 nm, and advantageously at least 3 nm. A portion of III-Nmaterial layer 220 between intervening material layer 250 and a QW layer655 closest to intervening material layer 250 may also have anythickness, but is advantageously less than 10 nm. In some furtherembodiments, III-N material layer 220 between intervening material layer250 and a QW layer 655 closest to intervening material layer 250 has athickness of at least 3 nm.

In light emitter structure 601, polarization junction 201 may have anyof the properties described above in the context of FIGS. 2 and 3. Asfurther illustrated in FIG. 6A, a terminal material 580 extends throughIII-N material layer 220 and intervening material layer 250,intersecting a region of III-N material layer 220 near where chargecarrier sheet 375 (2DHG) resides. In the example illustrated, a sidewallof terminal material 580 forms a junction with a sidewall of III-Nmaterial layer 220 within the region where charge carrier sheet 375resides. Hence, during operation much of the current between terminalmaterial 580 and III-N material layer 220 can be expected to occur atthis sidewall interface. This sidewall contact therefore allows holecurrent to bypass intervening material layer 250. Terminal material 580is operable as a low resistance semiconductor coupling to polarizationjunction 201 (i.e., to charge carrier sheet 375). In the embodimentshown, terminal material 580 is a III-N material having the same crystalorientation (e.g., −c polarity) as III-N material layer 220, and mayadvantageously include one or more impurity dopants imparting aconductivity type matching that of polarization junction 201 (e.g.,P-type). In some exemplary P-type embodiments, terminal material 580includes acceptor impurity dopants, such as, but not limited to, Mg.While III-N materials can be challenging to dope p-type, Mg dopantlevels of at least 1e17-1e18 atoms/cm³ are achievable in binary GaN, forexample. Terminal material 580 may form a homojunction with III-Nmaterial layer 220, or terminal material 580 may form a heterojunctionwith III-N material layer 220. Hence, terminal material 580 may have thesame, or different, majority lattice constituents as III-N materiallayer 220. In some advantageous embodiments, lower contact resistance topolarization junction 401 may be achieved where terminal material 580forms a heterojunction (e.g., abrupt or graded) with III-N materiallayer 220. In some exemplary embodiments, terminal material 580 has anarrower band gap than that of III-N material layer 220. For example,terminal material 580 may be a III-N alloy that includes more Indium(In) than III-N material layer 220. In some embodiments, terminalmaterial 580 is acceptor-doped In_(x)Ga_(1-x)N, (e.g., where x isbetween 0.05 and 0.2).

In some embodiments, terminal material 580 is crystalline, and may besubstantially monocrystalline. In the embodiments illustrated by FIG.6A, terminal material 580 has substantially the same crystal orientationas III-N material layer 220 (e.g., +c). An amorphous sidewall material640 may surround terminal material 580 and at least separate terminalmaterial 580 from III-N material layer 220 that has the inverted crystalorientation (e.g., −c). Sidewall material 640 may be any dielectric(e.g., SiO, SiON, SiN). Sidewall material 640 may also be electricallyconductive (e.g., a metal) as electrical isolation between terminalmaterial 580 and III-N material layer 230 may be unimportant in thecontext of light emitter operation. In alternative embodiments whereterminal material 580 polycrystalline, or lacks any long-range order,terminal material 580 may be in direct contact with both III-N materiallayer 220 and 230. Terminal material 580 forms a semiconductor-metaljunction with contact metal 590. Contact metal 590 may include any metalknown to be suitable for providing a non-rectifying contact (e.g., ohmicor tunneling metal-semiconductor junction) to terminal material 580. Insome exemplary embodiments, contact metal 590 includes at least onemetal, such as Ni, Pt, Pd, or W.

Each the III-N material layers in light emitter structure 601 may be ofa unique III-N alloy composition. Each of the III-N material layers mayalso be any of those compositions described above in the context oflight emitter structures 301 and 501. In the illustrated embodimenthowever, III-N material layer 220 has the same composition as III-Nmaterial layer 230 so that the polarization fields are both P2.

FIG. 6B is a cross-sectional view of a light emitter structure 602employing a QW structure between a P-type polarization junction and anN-type impurity-doped terminal, in accordance with some alternativeembodiments. Light emitter structure 602 has a planar architecture withtwo light emitter terminals on a top side of the QW structure. The QWstructure is therefore located between the terminals and a polarizationjunction with one of the terminals making contact to a charge carriersheet induced by the polarization junction. The other terminal iscoupled to the QW structure through an impurity-doped semiconductor.During operation of a light emitter incorporating light emitterstructure 602, current will generally be lateral (e.g., x-dimension)between the contact metallizations 390, 590 and through a thickness ofthe QW structure on a top side of polarization junction 201. In lightemitter structure 602, with the QW structure above intervening materiallayer 250 charge carrier sheet 376 may be leveraged to inject holes intoat least one QW layer 655.

As shown in FIG. 6B, light emitter structure 602 also includes terminalmaterial 380 and a contact metallization 390, which may each have any ofthe properties described above in the context of FIG. 6A. In thisembodiment however, terminal material 380 forms a junction with III-Nmaterial layer 230 and may have the same crystal orientation as III-Nmaterial layer 230. III-N material layer 230 may again have any of theproperties described above (e.g., in the context of FIG. 6A). In theexample illustrated in FIG. 6B, III-N material layer 230 has −c polarityand interfaces with intervening material layer 250. Terminal material380 may also have −c polarity. Alternatively, terminal material 380 maybe polycrystalline or amorphous. Within III-N material layer 230, is oneor more QW layer 655. QW layer(s) 655 may have any of the propertiesdescribed above. In the example illustrated in FIG. 6B, QW layer(s) 655also has −c polarity. Between QW layer(s) 655 and intervening materiallayer 250, charge carrier sheet 376 resides within a portion of III-Nmaterial layer 230. A portion of III-N material layer 230 betweenterminal material 380 and a first QW layer 655 may have any thickness,but is advantageously less than 10 nm. In some further embodiments,III-N material layer 230 between terminal material 380 and a first QWlayer 655 has a thickness less than 10 nm, and advantageously at least 3nm. A portion of III-N material layer 230 between intervening materiallayer 250 and a QW layer 655 closest to intervening material layer 250may also have any thickness, but is advantageously less than 10 nm. Insome further embodiments, a portion of III-N material layer 230 betweenintervening material layer 250 and a QW layer 655 closest to interveningmaterial layer 250 has a thickness of at least 3 nm.

Polarization junction 201 may have any of the properties described abovein the context of FIGS. 2 and 3, and may be located over or above anyterminal layer 305 known to be suitable for semiconductor light emitterapplications. As further illustrated in FIG. 6A, terminal material 580extends into III-N material layer 230, through QW layer(s) 655, andintersects an area of III-N material layer 230 near where charge carriersheet 376 (2DHG) resides. This terminal junction therefore scales withthe footprint of terminal material 580. An isolation dielectric material710 laterally (e.g., x-dimension) separates the anode and cathodeterminals of light emitter structure 602. Isolation dielectric material710 may be any material known to be suitable for electrical deviceisolation, such as any dielectric material used for shallow trenchisolation (STI) or interlayer dielectric (ILD) applications. In someembodiments, isolation dielectric material 710 includes both silicon andoxygen (e.g., SiO, SiON, SiOC(H), etc.). Isolation dielectric material710 extends through the QW layer(s) 655, preventing leakage current thatcould otherwise bypass QW layer(s) 655.

Each the III-N material layers in light emitter structure 602 may be ofa unique III-N alloy composition. Each of the III-N material layers mayalso be any of those compositions described above in the context oflight emitter structures 301 and 501. In the illustrated embodimenthowever. III-N material layer 220 has the same composition as III-Nmaterial layer 230 so that the polarization fields are both P2.

FIG. 7 is a cross-sectional view of a light emitter structure 701employing a QW structure between two polarization junctions, inaccordance with some embodiments. Light emitter structure 701 replacesan impurity-doped semiconductor terminal of type in light emitterstructures 601 and 602 with a second polarization junction. This secondpolarization junction is of complementary type to that employed in lightemitter structures 601 and 602. Hence, as shown in FIG. 7, QW layer(s)655 are located between two complementary polarization junctions. Theheterostructure stack employed in light emitter structure 701 istherefore a stack of the light emitter structure 301 over light emitterstructure 501. These two structures introduced separately above arestacked to share one QW structure. The reference numbers introduced inthe context of FIG. 2-FIG. 6B are retained in light emitter structure701 for material layers that may have any of the properties as describedfor those layers above. As further shown, for example, the N-face ofIII-N material layer 220 forms polarization junction 401. The GroupIII-face of III-N material layer 220 forms polarization junction 201. InFIG. 7, the suffixes “A” and “B” are added to reference numbers toemphasize how polarization junctions 201 and 401 are incorporated intolight emitter structure 701. Material layers with reference numbersending with “A” and “B” may have any of the properties described formaterial layers of the same root reference number. Hence, for lightemitter structure 701 intervening material layers 250A and 250B may bothhave any of the properties described above for intervening materiallayer 250. Likewise III-N material layers 230A and 230B may both haveany of the properties described above for III-N material layer 230.

Each the III-N material layers in light emitter structure 701 may be ofa unique III-N alloy composition. Each of the III-N material layers mayalso be any of those compositions described above in the context oflight emitter structures 301 and 501. In one exemplary embodimenthowever, III-N material layer 220 has the same composition as III-Nmaterial layers 230A and 230B located on opposite faces of III-Nmaterial layer 220 so the polarization fields are all P2. In someembodiments, III-N material layer 220 and III-N material layers 230A and230B are all binary GaN. III-N material layer 220 and III-N materiallayers 230A and 230B may also all be doped or undoped (i.e., notintentionally doped with donor or acceptor impurities).

Light emitter structure 701 includes a first (bottom) III-N materiallayer 230A that is over any suitable substrate (not depicted). III-Nmaterial layer 220 is above a first (bottom) intervening material layer250A that is over the first III-N material layer 230A. III-N materiallayer 220 includes a QW structure (e.g., QW layers 655). Anotherintervening material layer 250B is over III-N material layer 220.Another (top) III-N material layer 230B is over intervening materiallayer 250B. Within light emitter structure 701, III-N material layer 220may be operative as an intrinsic (i) layer of a diode with p-type andn-type junctions at opposite faces of III-N material layer 220. III-Nmaterial layer 220 should be of sufficient thickness to avoidband-to-band tunneling between 2DHG 375 and 2DEG 576. In someembodiments, III-N material layer 220 has a thickness greater than thatof at least one of III-N material layers 230A and 230B. In someembodiments, III-N material layer 220 has a thickness greater than thatof each of III-N material layers 230A and 230B. In some exemplaryembodiments, III-N material layer 220 is no more than 30 nm in thickness(e.g., along c-axis), while the thicknesses of III-N material layers230A and 230B may each vary as described above for III-N material layer220. In the illustrated embodiment, each of the depicted layers are indirect contact with the material layer above and below. However, one ormore other material layers (not depicted) may be inserted betweenvarious ones of the illustrated layers. Furthermore, an architecturefunctionally similar to light emitter structure 701 may be implementedby laterally arranging these same materials into a horizontal layoutrather than the vertical layout shown.

Semiconductor terminal materials 380 and 580 both extend through one ofthe polarization junctions. Terminal material 380 extends through, or isadjacent to, a sidewall of III-N material layer 230B, interveningmaterial layer 250B, and QW layer(s) 655. Terminal material 380intersects an area of III-N material layer 220 proximal (e.g., within afew nanometers) to negative charge carrier sheet 576. Electricalcoupling to charge carrier sheet 576 is therefore a function of thelateral area (e.g., footprint) of terminal material 380. Terminal 580extends through, or is adjacent to, a sidewall of, III-N material layer230B, intervening material layer 250B, and a portion of III-N materiallayer 220 where charge carrier sheet 375 resides. Electrical coupling tocharge carrier sheet 375 is therefore a function of the sidewall surfacearea forming a junction with a sidewall of III-N material layer 220where charge carrier sheet 375 resides. As described above, terminallayer 380 may be doped with donor impurities (e.g., Si) while terminallayer 580 may be doped with acceptor impurities (e.g., Mg). Contactmetals 390 and 590 may be any of suitable composition, for examplehaving any of the compositions described above.

Light emitter structure 701 has the advantage of high negative andpositive charge densities resulting from the polarization properties ofthe III-N material system. These high charge densities are concentratedin only a few nanometers of film thickness at the opposite faces ofIII-N material layer 220. Charge induction for light emitter structure701 is therefore not dependent on impurity dopant concentration. Thefunctional role of any doped material layers (e.g., terminal layers 380and 580) within light emitter structure 701 is limited to providing aterminal junction. Light emitter structure 701 also has the advantage ofcarrier blocking by intervening material layers 250A and 250B located onboth sides of the QW structure. Carriers may therefore be confined toreduced non-radiative recombination. Light emitter structure 701 alsohas carrier injection that avoids the blocking effect of the interveningmaterial layers.

Light emitters employing polarization junctions, such as light emitterstructures 301, 501, 601, 602, or 701, may be implemented as discretedevices or, monolithically integrated into an integrated circuit (IC)that further includes other devices, such as, but not limited totransistors. Such transistors may, for example, also be implemented inthe III-N material system. For example, an IC may include one or moreIII-N heterojunction field effect transistors (HFETs) electricallyinterconnected with one or more III-N polarization junction diodes. SuchHFETs may rely on polarization layers, or also employ polarizationjunction. In some embodiments where the NMOS HFET structure includes apolarization layer, the polarization layer is deposited over one of theIII-N material layers employed in a light emitter structure. Forexample, the polarization layer may be deposited on III-N material layer220 or III-N material layer 230. Such a polarization layer may be aIII-N material having the same crystal polarity as III-N material layer220 or III-N material layer 230 to which the polarization layercontacts. In some exemplary embodiments, the polarization layercomposition is sufficiently different from that of the III-N materiallayer 220 and III-N material layer 230 to induce a charge carrier sheet(e.g., 2DEG) within the III-N material layer 220 and III-N materiallayer 230. The HFET therefore may share at least one of III-N materiallayer 220 and III-N material layer 230 with a light emitter structure.

The HFET may further include a gate stack (e.g., a gate electrodeseparated from the III-N material layer 220 and III-N material layer 230by a gate dielectric), and a source and a drain on opposite sides of thegate stack according to any III-N HFET architecture as embodimentsherein are not limited in this respect. The polarization layer islocated between the gate and each of the source and the drain to inducea charge carrier sheet that couples the source and drain together undersuitable gate bias. The HFET source or drain may be of the same III-Nmaterial as one of the III-N terminal materials employed by polarizationdiodes described above, for example. In other embodiments, an IC mayinclude one or more silicon metal-oxide-semiconductor (MOS) FETselectrically interconnected with one or more III-N polarization junctiondiodes. Such silicon-based MOSFETs may have any device architectureknown in the art as embodiments herein are not limited in this respect.

The semiconductor light emitter structures described above may befabricated using a variety of methods. FIG. 8 is a flow diagramillustrating methods 801 for forming a III-N polarization junctiondiode, in accordance with some illustrative embodiments. Methods 801begin at operation 805 where a substrate including a crystalline seedlayer is received. The substrate received at operation 805 may be anysuitable for epitaxial growth of a III-N material stack, for example.The substrate received at operation 805 may, but need not, include oneor more terminal material layers to which a contact may be subsequentlyformed.

At operation 810, an epitaxial growth process is employed to form aIII-N material layer having a first crystal polarity on the substrateseeding surface. Such epitaxial growth may form a continuous crystalover an entire surface of a substrate, or may be limited to crystallineislands or mesas occupying only a portion of a substrate surface ascontrolled through a templating pattern. Polarity of the crystal growthmay be controlled through growth conditions, for example by introducingprecursors under growth conditions (e.g., temperature and partialpressures) that favor nucleation having either −c or +c polarity out ofthe plane of the seeding substrate surface. One or more III-N materiallayers having the first crystal polarity may be grown at operation 810.In the example shown in FIG. 9A, III-N material layer 230A is grown with(−c) polarity out of the plane of substrate 901. III-N material layer230A may have any of the compositions described above. For example,terminal material 380 may be an impurity-doped III-N material whileIII-N material layer 230A is intrinsic binary GaN. III-N material layer230A may be epitaxially grown over a substrate 901 with any growthtechnique(s) known to be suitable for III-N crystals, such as, but notlimited to, metal-organic chemical vapor deposition (MOCVD), vapor phaseepitaxy (VPE), or molecular beam epitaxy (MBE). In some embodiments,elevated temperatures of 600° C., or more, are employed. The growth ofIII-N material layer 230A may include deposition of a nucleation layer(not depicted), such as AlN, and further include growth of intrinsic GaNusing predetermined epitaxial growth conditions (e.g., a first growthpressure, a first growth temperature, a first VII growth precursorratio).

In further reference to FIG. 9A, substrate 901 may include any suitablematerial or materials. For example, substrate 901 may have cubiccrystallinity with a predetermined crystal orientation (e.g., (100),(111), (110), or the like). For such embodiments, template structuresmay be formed on a cubic substrate surface, such as a (100) surface.III-N crystals may also be grown on other surfaces (e.g., 110, 111,miscut or offcut, for example 2-10° toward (110), etc.). In some suchexamples, substrate 901 includes a semiconductor material such asmonocrystalline silicon (Si), germanium (Ge), silicon germanium (SiGe).Other crystalline materials, such as, but not limited to, galliumarsenide (GaAs), or silicon carbide (SiC), sapphire (Al₂O₃) are alsosuitable as a growth surface of substrate 901. In some examples,substrate 901 includes silicon having a (100) crystal orientation with a4°-11° miscut (with 4-6° being particularly advantageous). In otherexamples, substrate 901 includes silicon with a crystal orientation of(111), which may offer the advantage of a smaller lattice mismatch withIII-N materials than (100) or (110) silicon surfaces. Substrate 901 mayinclude one or more buffer layers of III-N material. Substrate 901 mayalso include a host substrate material upon which a III-N crystal hasbeen bonded, in which case the host substrate may be crystalline, or not(e.g., glass, polymer, etc.). In various examples, substrate 901 mayinclude metallization interconnect layers for integrated circuits orelectronic devices such as transistors, memories, capacitors, resistors,optoelectronic devices, switches, or any other active or passiveelectronic devices separated by an electrically insulating layer, forexample, an interlayer dielectric, or the like.

Returning to FIG. 8, methods 801 continue at operation 815 where a firstintervening material layer is formed above the III-N material layerhaving the first crystal polarity. As noted above, the interveningmaterial layer is to decouple the crystal polarity of two adjacent III-Nmaterial layers and thereby facilitate a polarity inversion. In someembodiments, operation 815 entails an epitaxial growth of a precursormaterial that is suitable as a nucleation layer for III-N epitaxialgrowths. In the example shown in FIG. 9B, intervening material layer250A may have been epitaxially grown or deposited (e.g., by atomic layerdeposition) directly on the III-N material layer 230A. Such a precursormaterial may also have the first crystal polarity, for example, or analternative crystal polarity, or alternative crystallinity (e.g.,trigonal or cubic), or may be amorphous in the as-deposited state. Insome embodiments, operation 815 further entails an oxidation of theprecursor material epitaxially grown over the III-N material layer. Forexample, a binary AlN layer with the first crystal polarity may be grownat operation 815 and then subsequently oxidized, for example with anyin-situ or ex-situ oxidation technique known to be suitable for at leasta surface of a crystalline or amorphous AlN layer. If the AlN isamorphous as-deposited, a thermal process may be performed before orafter oxidation to at least partially melt the amorphous material andinduce crystallization. This oxidized surface (e.g., Al_(x)O_(y)) maythen be advantageous for inverting the polarity of III-N material duringsubsequent epitaxial growth processes. Similar growth and oxidationprocesses may also be performed to form other material compositions,such as, but not limited to, Sc_(x)O_(y) or AlScO.

In some alternative embodiments, operation 815 includes the depositionof an amorphous or polycrystalline material that is suitable as abonding layer between two III-N material layers. Any deposition processknown to be suitable for any of the exemplary materials described abovemay be employed to form the amorphous or polycrystalline interveningmaterial layer over. For example, chemical vapor deposition (CVD),plasma-enhanced CVD (PECVD), or atomic layer deposition (ALD) may beemployed at operation 815 to deposit a silicon oxide, or any of thehigh-k materials described above.

Methods 801 continue at operation 820 where a III-N layer having asecond crystal polarity, substantially opposite to, or inverted from,the first crystal polarity is formed above the intervening materiallayer deposited at operation 815. In the example shown in FIG. 9C, III-Nmaterial layer 220 has been formed directly on intervening materiallayer 250A. Polarity of the crystal growth at operation 820 may becontrolled through growth conditions, for example by introducingprecursors under growth conditions (e.g., temperature and partialpressures) that favor nucleation having either −c or +c polarity out ofthe plane of the seeding substrate surface. One or more III-N materiallayers having the second crystal polarity may be grown at operation 820.In the example shown in FIG. 9C, III-N material layer 220 is grown with(+c) polarity out of the plane of substrate 901. In some embodimentswhere operation 820 entails the growth of multiple III-N materiallayers, both a nucleation layer and a bulk III-N layer of greaterthickness are epitaxially grown. For example, a nucleation layer of amaterial other than binary GaN (e.g., AlN) may be epitaxially grown onthe intervening material layer (e.g., Al_(x)O_(y)). With proper growthconditions, the nucleation layer may initiate epitaxial growth with thedesired (+c) polarity, and operation 820 may continue with the growth ofany additional III-N material (e.g., binary GaN). The epitaxial growthof III-N material layer 220 may be terminated upon reaching a desiredtarget thickness. As shown in FIG. 9C, polarization doping (e.g., 2DEGs575, 576) occurs upon the formation of III-N material layer 220.

In alternative embodiments, for example where an amorphous orpolycrystalline intervening material layer was deposited or otherwiseformed at operation 815, layer transfer and/or wafer bonding processesmay be practiced at operation 820. For example, one or more crystallineIII-N material layers having the desired second crystal polarity may beprovided on a sacrificial substrate. The sacrificial substrate may be,for example, any of the materials described above for substrate 901. Inone such embodiment, a III-N material having a desired composition isgrown with (−c) polarity over the sacrificial substrate. This structureis then inverted to mate a surface of this III-N material to a surfaceof the intervening material layer, thereby providing the desired (−c) to(+c) polarity inversion. The sacrificial substrate may then be removed,if desired.

Returning to FIG. 8, methods 801 continue at operation 825 where anotherintervening material layer is formed over the III-N layer having thesecond crystal polarity. As noted above, this second interveningmaterial layer is also to decouple the crystal polarity of two adjacentIII-N material layers and thereby facilitate another polarity inversion,substantially in the same manner as the first inversion. In someembodiments, operation 825 entails an epitaxial growth of a materialthat is suitable as a nucleation layer for further III-N epitaxialgrowths. In some embodiments, operation 825 is the same as operation815. Methods 801 then continue at operation 830 where a third III-Nlayer having crystal polarity inverted from the second polarity (i.e.,inverted back to the first polarity) is formed above the interveningmaterial layer that was formed at operation 825.

In the example shown in FIG. 9D, any of the materials described abovemay be epitaxially grown or deposited (e.g., by atomic layer deposition)directly on the III-N material layer 220. As deposited, this materialmay also have the second crystal polarity, for example. In someembodiments, operation 825 further entails an oxidation of precursormaterial epitaxially grown over the III-N material layer having thesecond crystal polarity, the first polarity, alternative polarity, orother crystallinity (e.g., trigonal or cubic), or may be amorphous inthe as-deposited state. For example, a binary AlN layer with the secondcrystal polarity may be grown at operation 825 as a precursor materialand then subsequently oxidized, for example with any in-situ or ex-situoxidation technique known to be suitable for oxidizing at least asurface of a crystalline or amorphous AlN layer. If the AlN is amorphousas-deposited, a thermal process may be performed before or afteroxidation to at least partially melt the amorphous material and inducecrystallization. This oxidized surface (e.g., Al_(x)O_(y)) may then beadvantageous for inverting the polarity of III-N material duringsubsequent epitaxial growth processes. Similar growth and oxidationprocesses may also be performed to form other material compositions,such as, but not limited to Sc_(x)O_(y) or AlScO.

In some alternative embodiments, operation 825 includes the depositionof an amorphous or polycrystalline material that is suitable as abonding layer between two III-N material layers. Any deposition processknown to be suitable for any of the exemplary materials described abovemay be employed to form an amorphous or polycrystalline interveningmaterial layer over. For example, chemical vapor deposition (CVD),plasma-enhanced CVD (PECVD), or atomic layer deposition (ALD) may beemployed at operation 825 to deposit a silicon oxide, or any of thehigh-k materials described above.

In the example shown in FIG. 9D, III-N material layer 230B has beenformed directly on intervening material layer 250B. Polarity of thecrystal growth may be controlled through growth conditions, for exampleby introducing precursors under growth conditions (e.g., temperature andpartial pressures) that favor nucleation having either −c or +c polarityout of the plane of the seeding substrate surface. One or more III-Nmaterial layers having the first crystal polarity may be grown atoperation 830. In the example shown in FIG. 9D, III-N material layer230B is grown with (−c) polarity out of the plane of interveningmaterial layers 250A, 250B and/or substrate 901. In some embodimentswhere operation 830 entails the growth of multiple III-N materiallayers, both a nucleation layer and a bulk III-N layer of greaterthickness are epitaxially grown. For example, a nucleation layer of amaterial other than binary GaN (e.g., AlN) may be epitaxially grown onthe intervening material layer (e.g., Al_(x)O_(y)). With proper growthconditions, the nucleation layer may initiate epitaxial growth with thedesired (−c) polarity, and operation 830 may continue with the growth ofany additional III-N material (e.g., binary GaN). The epitaxial growthof III-N material layer 230B may be terminated upon reaching a desiredtarget thickness. As shown in FIG. 9D, polarization doping (e.g., 2DHGs575, 576) occurs upon the formation of III-N material layer 220B.

In alternative embodiments, for example where an amorphous orpolycrystalline intervening material layer was deposited or otherwiseformed at operation 825, layer transfer and/or wafer bonding processesmay be practiced at operation 830. Such bonding and/or layer transfermay proceed as a second iteration of a bonding/transfer processperformed at operation 815. Alternatively a stack of material layersincluding a polarization junction fabricated upstream by any means maybe transferred and/or bonded at operation 815 or operation 830 to arriveat the same final structure. For example, one or more crystalline III-Nmaterial layers having the desired first crystal polarity may beprovided on a sacrificial substrate. The sacrificial substrate may be,for example, any of the materials described above for substrate 901. Inone such embodiment, a III-N material having a desired composition isgrown with (+c) polarity over the sacrificial substrate. This structureis then inverted to mate a surface of this III-N material to a surfaceof the intervening material layer, thereby fabricating in the desired(+c) to (−c) polarity inversion. The sacrificial substrate may then beremoved.

Returning to FIG. 8, methods 801 complete at operation 835 where one ormore interconnect levels, for example including light emitter contactmetallization, are formed using any techniques known to be suitable forthe purpose. For embodiments where the light emitter structures are tobe monolithically integrated into an IC, any known back-end-of-line(BEOL) processing may be performed at operation 835 to complete the IC.Following operation 835, an IC including III-N polarization junctionlight emitters, or discrete III-N polarization junction light emittersare substantially complete and may be singulated and packaged followingany suitable techniques.

As further shown in FIG. 9E, a trench 975 is etched through III-Nmaterial layer 230B, through intervening material layer 250B, andpartially through III-N material layer 220 at least to the extent thatthe QW layer(s) 655 are etched through. One or more etch processessuitable for the material compositions may be utilized to form trench975. Trench 975 is then at least partially backfilled with isolationdielectric material 710. In some embodiments, trench 975 is completelybackfilled with isolation dielectric material 710, for example using anySTI process where a polish planarizes a top surface of isolationdielectric material 710 with III-N material layer 230B. Alternatively,trench 975 is only partially backfilled with isolation dielectricmaterial 710, for example using a conformal dielectric depositionprocess followed by an anisotropic dielectric etch process to form asidewall spacer of isolation dielectric material 710, as illustrated inFIG. 9E.

As further shown in FIG. 9F, terminal material 380 is deposited and/orgrown from within a remainder of trench 975. For alternative embodimentswhere trench 975 is completely backfilled with isolation dielectricmaterial 710, another (second) trench may be etched through III-Nmaterial layer 230B, through intervening material layer 250B, andpartially through III-N material layer 220. This second trench may thenbe backfilled with terminal material 380 to arrive at a similarstructure. In still other embodiments, a portion of isolation dielectricmaterial 710 occupying trench 975 is etched to re-expose a portion ofIII-N material layer 220. This opening is then backfilled with terminalmaterial 380.

As further shown in FIG. 9G, another trench is then etched through theIII-N material layer 230B, through intervening material layer 250B, andpartially through III-N material layer 220 to the extent that a sidewallof III-N material layer 220 where the carrier sheet 375 is exposed. Oneor more etch processes suitable for the material compositions may beemployed for this etch. Relative to trench 975 (FIG. 10B), the thicknessof III-N material layer 220 removed is less. Terminal material 380 isthen deposited and or grown within this trench. One or moreplanarization processes (e.g., a polish) may be performed to planarize atop surface of terminal materials 380, 580 with a top surface of III-Nmaterial layer 230B. Contact metallization may then be deposited anpatterned according to any suitable techniques known in the art toarrive at the light emitter structure 701, as shown in FIG. 9H, and asdiscussed above in the context of FIG. 7.

FIG. 10 illustrates a system 1000 in which a mobile computing platform1005 or a data server machine 1010 employs an circuitry including atleast one III-N polarization junction light emitter, in accordance withsome embodiments. The server machine 1010 may be any commercial server,for example including any number of high-performance computing platformsdisposed within a rack and networked together for electronic dataprocessing, which in the exemplary embodiment includes circuitry 1050.In accordance with mobile embodiments of system 1000, mobile computingplatform 1005 may be any portable device configured for each ofelectronic data display, electronic data processing, wireless or opticalelectronic data transmission, or the like. For example, the mobilecomputing platform 1005 may be any of a tablet, a smart phone, laptopcomputer, etc., and may include a display screen (e.g., a capacitive,inductive, resistive, or optical touchscreen), a chip-level orpackage-level integrated system 1090, and a battery 1015.

Whether disposed within the integrated system 1090 illustrated in theexpanded view 1020, or as a stand-alone packaged chip within the servermachine 1010, an IC is electrically coupled to at least one III-Npolarization junction light emitter, for example as describe elsewhereherein. The circuitry 1050 may be further affixed to a board, asubstrate, or an interposer 1060 along with a power managementintegrated circuit (PMIC). Functionally, PMIC 1030 may perform battenpower regulation, DC-to-DC conversion, etc., and so has an input coupledto battery 1015 and with an output providing a current supply to otherfunctional modules.

Circuitry 1050, in some embodiments, includes RF (wireless) integratedcircuitry (RFIC) further including a wideband RF (wireless) transmitterand/or receiver (TX/RX transceiver including a digital baseband and ananalog front end module comprising a power amplifier on a transmit pathand a low noise amplifier on a receive path). The RFIC includes at leastone III-N heterostructure transistor or diode. The RFIC has an outputcoupled to an antenna (not shown) to implement any of a number ofwireless standards or protocols, including but not limited to Wi-Fi(IEEE 802.10 family), WiMAX (IEEE 802.16 family), IEEE 802.20, long termevolution (LTE), Ev-DO, HSPA+, HSDPA+, HSUPA+, EDGE, GSM, GPRS, CDMA,TDMA, DECT, Bluetooth, derivatives thereof, as well as any otherwireless protocols that are designated as 3G, 4G, 5G, and beyond.Circuitry 1050, in some embodiments, includes an optical transmitterand/or receiver (TX/RX transceiver) including a III-N polarizationjunction light emitter.

FIG. 11 is a functional block diagram of a computing device 1100,arranged in accordance with at least some implementations of the presentdisclosure. Computing device 1100 may be found inside platform 1005 orserver machine 1010, for example. Device 1100 further includes amotherboard 1102 hosting a number of components, such as, but notlimited to, a processor 1104 (e.g., an applications processor), whichmay further include at least one III-N polarization junction diode, inaccordance with embodiments of the present invention. Processor 1104 mayfor example include power management integrated circuitry (PMIC) thatincludes at least one III-N polarization junction diode. Processor 1104may be physically and/or electrically coupled to motherboard 1102. Insome examples, processor 1104 includes an integrated circuit diepackaged within the processor 1104. In general, the term “processor” or“microprocessor” may refer to any device or portion of a device thatprocesses electronic data from registers and/or memory to transform thatelectronic data into other electronic data that may be further stored inregisters and/or memory.

In various examples, one or more communication chips 1106 may also bephysically and/or electrically coupled to the motherboard 1102. Infurther implementations, communication chips 1106 may be part ofprocessor 1104. Depending on its applications, computing device 1100 mayinclude other components that may or may not be physically andelectrically coupled to motherboard 1102. These other componentsinclude, but are not limited to, volatile memory (e.g., MRAM 1130, DRAM1132), non-volatile memory (e.g., ROM 1135), flash memory, a graphicsprocessor 1122, a digital signal processor, a crypto processor, achipset, an antenna 1125, touchscreen display 1115, touchscreencontroller 1175, battery 1110, audio codec, video codec, power amplifier1121, global positioning system (GPS) device 1140, compass 1145,accelerometer, gyroscope, audio speaker 1120, camera 1141, and massstorage device (such as hard disk drive, solid-state drive (SSD),compact disk (CD), digital versatile disk (DVD), and so forth), or thelike.

Communication chips 1106 may enable wireless communications for thetransfer of data to and from the computing device 1100. The term“wireless” and its derivatives may be used to describe circuits,devices, systems, methods, techniques, communications channels, etc.,that may communicate data through the use of modulated electromagneticradiation through a non-solid medium. The term does not imply that theassociated devices do not contain any wires, although in someembodiments they might not. Communication chips 1106 may implement anyof a number of wireless standards or protocols, including but notlimited to those described elsewhere herein. As discussed, computingdevice 1100 may include a plurality of communication chips 1106. Forexample, a first communication chip may be dedicated to shorter-rangewireless communications, such as Wi-Fi and Bluetooth, and a secondcommunication chip may be dedicated to longer-range wirelesscommunications such as GPS, EDGE, GPRS, CDMA, WiMAX, LTE, Ev-DO, andothers.

While certain features set forth herein have been described withreference to various implementations, this description is not intendedto be construed in a limiting sense. Hence, various modifications of theimplementations described herein, as well as other implementations,which are apparent to persons skilled in the art to which the presentdisclosure pertains are deemed to lie within the spirit and scope of thepresent disclosure.

It will be recognized that the invention is not limited to theembodiments so described, but can be practiced with modification andalteration without departing from the scope of the appended claims. Forexample the above embodiments may include specific combinations offeatures as further provided below.

In one or more examples, a light emitter structure, comprises a quantumwell (QW) structure with a first layer comprising a Group III-nitride(III-N) material having a first crystal polarity. The light emitterstructure has a second layer comprising a III-N material having a secondcrystal polarity, inverted from the first crystal polarity. The lightemitter structure has an intervening material layer between the QWstructure and the second layer, wherein the intervening material layercomprises other than a III-N material. A first contact and a secondcontact is electrically coupled across the QW structure.

In one or more second examples, for any of the first examples, the firstcontact is electrically coupled to the first layer through a terminallayer comprising a III-N alloy and having a higher concentration ofacceptor impurities than the first layer, and the QW structure isbetween the intervening material layer and the second contact.

In one or more third examples, for any of the first through the secondexamples, a sidewall of the terminal material contacts a sidewall of thefirst layer proximal to a positive charge carrier sheet that is near theinterface of the first layer and the intervening material layer.

In one or more fourth examples, for any of the first through the thirdexamples the QW structure comprises the first layer and one or more QWlayers having a bandgap smaller than that of the first layer. The firstcontact is electrically coupled to the first layer through a firstterminal material comprising a III-N alloy having a higher concentrationof acceptor impurities than the first layer. The second contact iselectrically coupled to the second layer through a second terminalmaterial comprising a III-N alloy having a higher concentration of donorimpurities than the second layer. An isolation dielectric materiallaterally separates the first terminal material from the second terminalmaterial, from the second layer, and from the QW layers.

In one or more fifth examples, for any of the first through the fourthexamples, a bottom of the first III-N terminal material contacts an areaof a positive charge carrier sheet that is near the interface of thefirst layer and the intervening material layer.

In one or more sixth examples, for any of the second examples the lightemitter structure further comprises a third layer comprising a III-Nmaterial having the second crystal polarity, a second interveningbetween the first layer and the third layer, wherein the secondintervening material layer comprises other than a III-N material. Thesecond contact is coupled to a negative charge carrier sheet that isnear the interface of the first III-N material and the secondintervening material layer through a second terminal material comprisinga III-N alloy having a higher concentration of donor impurities than thefirst layer.

In one or more seventh examples, for any of the sixth examples a groupIII-face of the first layer is adjacent to one of the interveningmaterial layers and a nitrogen (N)-face of the second layer is adjacentto another of the intervening material layers. A group III-face of thesecond layer is facing the group III-face of the first layer. A nitrogen(N)-face of the third layer is facing the nitrogen (N)-face of the thirdlayer.

In one or more eighth examples, for any of the seventh examples a c-axisof the first, second and third layers is oriented substantially normalto a plane of the intervening material layers with polar faces of thefirst, second, and third layers separated by the intervening materiallayers.

In one or more ninth examples, for any of the seventh examples at leastthe first and third layers comprise the same III-N material, theterminal material has a higher concentration of Indium than the firstand third layers.

In one or more tenth examples, for any of the sixth through ninthexamples, a first terminal material comprising a III-N alloy contacts asidewall of the first layer proximal to a positive charge carrier sheetof a first polarization junction near the intervening material layer.The second terminal material comprising a III-N alloy contacts a surfaceof the first layer proximal to a negative charge carrier sheet of asecond polarization junction near the second intervening material layer.

In one or more eleventh examples, for any of the first through the tenthexamples, the light emitter structure further comprises an isolationdielectric material between the first and second terminal materials,wherein the isolation dielectric material extends through the firstpolarization junction but not the second polarization junction.

In one or more twelfth examples, for any of the first through theeleventh examples, the first layer is binary GaN.

In one or more thirteenth examples, for any of the first through thetwelfth examples the intervening material layers each have a thicknessno more than 5 nm.

In one or more fourteenth examples, for any of the first through thethirteenth examples the intervening material layers each comprise oxygenand at least one of a metal, a rare earth, or a lanthanide.

In one or more fifteenth examples, for any of the first through thefourteenth examples the intervening material layers are crystalline.

In one or more sixteenth examples, for any of the first through thefifteenth examples the intervening material layers are amorphous.

In one or more seventeenth examples, a computer platform includes aprocessor, and one or more optical transceiver coupled to the processor,wherein the optical transceiver includes a light emitter. The lightemitter comprises a quantum well (QW) structure with a first layercomprising a Group III-nitride (III-N) material having a first crystalpolarity. The light emitter comprises a second layer comprising a III-Nmaterial having a second crystal polarity, inverted from the firstcrystal polarity. The light emitter comprises an intervening materiallayer between the QW structure and the second layer, wherein theintervening material layer comprises other than a III-N material. Thelight emitter comprises a first contact and a second contactelectrically coupled across the QW structure.

In one or more eighteenth examples, the computer platform comprises abattery coupled to at least one of the processor and RF transceiver.

In one or more nineteenth examples, a method of forming a light emitter,the method comprises epitaxially growing a quantum well (QW) structureover a crystalline seed layer, wherein the QW structure has a firstlayer comprising a Group III-nitride (III-N) material of a first crystalpolarity, and one or more QW layers having a bandgap smaller than thatof the first layer. The method comprises depositing, over the QWstructure, an intervening material layer comprising other than a III-Nmaterial. The method comprises forming, over the first interveningmaterial layer, a second layer comprising a III-N material having asecond crystal polarity, opposite the first polarity. The methodcomprises forming a first contact to a positive charge carrier sheet ofa polarization junction near the intervening material layer. The methodcomprises forming a second contact to a III-N material separated fromthe first layer by the one or QW layers.

In one or more twentieth examples, the method further comprises forminga third layer comprising a III-N material of the first crystal polarity,depositing, over the third layer, a second intervening material layercomprising other than a III-N material. The QW structure is grown overthe second intervening material layer.

In one or more twenty-first examples, for any of the nineteenth throughtwenty-first examples forming at least one of the first and secondintervening material layers further comprises epitaxially depositing aprecursor material layer comprising Al, and oxidizing the precursormaterial layer.

In one or more twenty-second examples, for any of the nineteenth throughtwenty-first examples forming at least one of the first and secondintervening material layers further comprises chemical vapor depositionof an amorphous material, and forming the first layer further comprisesbonding a III-N material to the amorphous material.

In one or more twenty-third examples for any of the nineteenth throughtwenty-second examples forming the first contact further comprisesexposing a positive charge carrier sheet that is near the interface ofthe first layer and the intervening material layer by forming a firstopening through the second layer and through the first interveningmaterial layer. Forming the first contact further comprises epitaxiallygrowing a first terminal material comprising p-type In_(x)Ga_(1-x)Nwithin the first opening. Forming the second contact further comprisesexposing a negative charge carrier sheet that is near the interface ofthe first layer and the second intervening material layer by forming asecond opening through the second layer and through the firstintervening material layer. Forming the second contact further comprisesepitaxially growing a second terminal material comprising n-typeIn_(x)Ga_(1-x)N within the second opening. An isolation dielectric isformed between the first and second terminal materials.

In one or more twenty-fourth examples, for any of the twenty-thirdexamples forming the first, second, and third layers further comprisesepitaxially growing the III-N material with the c-axis orientedsubstantially normal to a plane of the intervening material layers.

In one or more twenty-fifth examples, for any of the twenty-thirdexamples forming the first layer further comprises epitaxially growingGaN with a Ga-face proximal to the first intervening material layer anda N-face proximal to the second intervening material layer. Forming thesecond layer further comprises epitaxially growing GaN with a Ga-faceproximal to the first intervening material layer. Forming the thirdlayer further comprises epitaxially growing GaN with a N-face proximalto the second intervening material layer.

However, the above embodiments are not limited in this regard and, invarious implementations, the above embodiments may include theundertaking only a subset of such features, undertaking a differentorder of such features, undertaking a different combination of suchfeatures, and/or undertaking additional features than those featuresexplicitly listed. The scope of the invention should, therefore, bedetermined with reference to the appended claims, along with the fullscope of equivalents to which such claims are entitled.

1-25. (canceled)
 26. A light emitter structure, comprising: a quantumwell (QW) structure with a first layer comprising a Group III-nitride(III-N) material having a first crystal polarity; a second layercomprising a III-N material having a second crystal polarity, invertedfrom the first crystal polarity; an intervening material layer betweenthe QW structure and the second layer, wherein the intervening materiallayer comprises other than a III-N material; and a first contact and asecond contact electrically coupled across the QW structure.
 27. Thelight emitter structure of claim 26, wherein: the first contact iselectrically coupled to the first layer through a terminal layercomprising a III—N alloy having a higher concentration of acceptorimpurities than the first layer; and the QW structure is between theintervening material layer and the second contact.
 28. The light emitterstructure of claim 27, wherein a sidewall of the terminal materialcontacts a sidewall of the first layer proximal to a positive chargecarrier sheet that is near the interface of the first layer and theintervening material layer.
 29. The light emitter structure of claim 26,wherein: the QW structure comprises the first layer and one or more QWlayers having a bandgap smaller than that of the first layer; the firstcontact is electrically coupled to the first layer through a firstterminal material comprising a III-N alloy having a higher concentrationof acceptor impurities than the first layer; the second contact iselectrically coupled to the second layer through a second terminalmaterial comprising a III-N alloy having a higher concentration of donorimpurities than the second layer; and an isolation dielectric materiallaterally separates the first terminal material from the second terminalmaterial, from the second layer, and from the QW layers.
 30. The lightemitter structure of claim 29, wherein a bottom of the first III-Nterminal material contacts an area of a positive charge carrier sheetthat is near the interface of the first layer and the interveningmaterial layer.
 31. The light emitter structure of claim 27, furthercomprising: a third layer comprising a III-N material having the secondcrystal polarity; a second intervening between the first layer and thethird layer, wherein the second intervening material layer comprisesother than a III-N material; and wherein the second contact is coupledto a negative charge carrier sheet that is near the interface of thefirst III-N material and the second intervening material layer through asecond terminal material comprising a III-N alloy having a higherconcentration of donor impurities than the first layer.
 32. The lightemitter structure of claim 31, wherein: a group III-face of the firstlayer is adjacent to one of the intervening material layers and anitrogen (N)-face of the second layer is adjacent to another of theintervening material layers; a group III-face of the second layer isfacing the group III-face of the first layer; and a nitrogen (N)-face ofthe third layer is facing the nitrogen (N)-face of the third layer. 33.The light emitter structure of claim 32, wherein a c-axis of the first,second and third layers is oriented substantially normal to a plane ofthe intervening material layers with polar faces of the first, second,and third layers separated by the intervening material layers.
 34. Thelight emitter structure of claim 32, wherein: at least the first andthird layers comprise the same III-N material; and the terminal materialhas a higher concentration of Indium than the first and third layers.35. The light emitter structure of claim 31, wherein: a first terminalmaterial comprising a III-N alloy contacts a sidewall of the first layerproximal to a positive charge carrier sheet of a first polarizationjunction near the intervening material layer; and the second terminalmaterial comprising a III-N alloy contacts a surface of the first layerproximal to a negative charge carrier sheet of a second polarizationjunction near the second intervening material layer.
 36. The lightemitter structure of claim 35, further comprising a dielectric materialbetween the first and second terminal materials, wherein the dielectricmaterial extends through the first polarization junction but not thesecond polarization junction.
 37. The light emitter structure of claim26, wherein the intervening material layers each comprise oxygen and atleast one of a metal, a rare earth, or a lanthanide.
 38. The lightemitter structure of claim 37, wherein the intervening material layersare crystalline.
 39. The diode structure of 37, wherein the interveningmaterial layers are amorphous.
 40. A computer platform including: aprocessor; and one or more optical transceiver coupled to the processor,wherein the optical transceiver includes the light emitter of claim 1.41. The computer platform of claim 40, further comprising a batterycoupled to at least one of the processor and optical transceiver.
 42. Amethod of forming a light emitter, the method comprising: epitaxiallygrowing a quantum well (QW) structure over a crystalline seed layer,wherein the QW structure has a first layer comprising a GroupIII-nitride (III-N) material of a first crystal polarity, and one ormore QW layers having a bandgap smaller than that of the first layer;depositing, over the QW structure, an intervening material layercomprising other than a III-N material; forming, over the firstintervening material layer, a second layer comprising a III-N materialhaving a second crystal polarity, opposite the first polarity; forming afirst contact to a positive charge carrier sheet of a polarizationjunction near the intervening material layer; and forming a secondcontact to a III-N material separated from the first layer by the one orQW layers.
 43. The method of claim 42, further comprising: forming athird layer comprising a III-N material of the first crystal polarity;and depositing, over the third layer, a second intervening materiallayer comprising other than a III-N material; and wherein the QWstructure is grown over the second intervening material layer.
 44. Themethod of claim 43, wherein forming at least one of the first and secondintervening material layers further comprises: epitaxially depositing aprecursor material layer comprising Al; and oxidizing the precursormaterial layer.